Re: [patch][vect]: when REALPART/IMAGPART also check their def stmts [PR126593]

On Tue, 4 Aug 2026, Tamar Christina wrote:

> The check in compatible_complex_nodes_p is a bit too loose in that we assumed
> that when we see a REAL/IMAG pair of statement in a TWO_OPERANDS they must have
> come from the same defining statement. 
> 
> This is of course too loose and the operands should be checked explicitly.
> 
> Bootstrapped Regtested on aarch64-none-linux-gnu,
> arm-none-linux-gnueabihf, x86_64-pc-linux-gnu
> -m32, -m64 and no issues.
> 
> Pushed.
> 
> Thanks,
> Tamar
> 
> gcc/ChangeLog:
> 
> 	PR tree-optimization/126593
> 	* tree-vect-slp-patterns.cc (compatible_complex_nodes_p): Check def
> 	stmts of real and imag pairs.
> 
> gcc/testsuite/ChangeLog:
> 
> 	PR tree-optimization/126593
> 	* gcc.target/aarch64/pr126593.c: New test.
> 
> ---
> diff --git a/gcc/testsuite/gcc.target/aarch64/pr126593.c b/gcc/testsuite/gcc.target/aarch64/pr126593.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..fce64d4d3393dc8456f37c5d7ecdc10d9fd23a04
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/pr126593.c
> @@ -0,0 +1,37 @@
> +/* { dg-do run { target arm_v8_3a_complex_neon_hw } } */
> +/* { dg-require-effective-target aarch64_little_endian } */
> +/* { dg-options "-O3 -march=armv8.3-a -ffast-math" } */
> +
> +#define N 64
> +_Complex float a[N], b[N], d[N], c[N];
> +
> +__attribute__((noipa))
> +void
> +mix (int n)
> +{
> +  for (int i = 0; i < n; i++)
> +    {
> +      __real__ c[i] = __real__ a[i] * __real__ b[i] - __imag__ a[i] * __imag__ d[i];
> +      __imag__ c[i] = __real__ a[i] * __imag__ b[i] + __imag__ a[i] * __real__ d[i];
> +    }
> +}
> +
> +int
> +main (void)
> +{
> +  for (int i = 0; i < N; i++)
> +    {
> +      a[i] = 1.0f + 2.0fi;
> +      b[i] = 3.0f + 4.0fi;
> +      d[i] = 5.0f + 6.0fi;
> +    }
> +
> +  mix (N);
> +
> +  /* scalar: re = 1*3 - 2*6 = -9, im = 1*4 + 2*5 = 14.
> +     vectorized as a*b: re = -5, im = 10.  */
> +  if (__real__ c[0] != -9.0f || __imag__ c[0] != 14.0f)
> +    __builtin_abort ();
> +
> +  return 0;
> +}
> diff --git a/gcc/tree-vect-slp-patterns.cc b/gcc/tree-vect-slp-patterns.cc
> index 3e2c0fe2c099348e055c2e08a7d899c9cbf71d49..2136329645cad8f26f672ac5ad7d7f225bb08b7f 100644
> --- a/gcc/tree-vect-slp-patterns.cc
> +++ b/gcc/tree-vect-slp-patterns.cc
> @@ -801,7 +801,10 @@ compatible_complex_nodes_p (slp_compat_nodes_map_t *compat_cache,
>        tree_code acode = gimple_assign_rhs_code (a_stmt);
>        tree_code bcode = gimple_assign_rhs_code (b_stmt);
>        if ((acode == REALPART_EXPR || acode == IMAGPART_EXPR)
> -	  && (bcode == REALPART_EXPR || bcode == IMAGPART_EXPR))
> +	  && (bcode == REALPART_EXPR || bcode == IMAGPART_EXPR)
> +	  && operand_equal_p (TREE_OPERAND (gimple_assign_rhs1 (a_stmt), 0),
> +			      TREE_OPERAND (gimple_assign_rhs1 (b_stmt), 0),
> +			      0))

Minor nit - you cal elide the last 0 argument to operand_equal_p.

OK.

Thanks,
Richard.

>  	return true;
>  
>        if (acode != bcode)
> 
> 
> 

-- 
Richard Biener <[email protected]>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Jochen Jaser, Andrew McDonald, Abhinav Puri; (HRB 36809, AG Nuernberg)